1 files changed, 73 insertions, 18 deletions
diff --git a/roundtrip_test.go b/roundtrip_test.go
index 71ca6d0..01d6f13 100644
--- a/roundtrip_test.go
+++ b/roundtrip_test.go
@@ -6,9 +6,9 @@ package lowmemjson_test
 
 import (
 	"bytes"
+	"encoding/json"
 	"os"
 	"path/filepath"
-	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -16,7 +16,7 @@ import (
 	"git.lukeshu.com/go/lowmemjson"
 )
 
-type ScanDevicesResult map[string]ScanOneDeviceResult
+type ScanDevicesResult map[uint64]ScanOneDeviceResult
 
 type ScanOneDeviceResult struct {
 	FoundExtentCSums []SysExtentCSum
@@ -27,27 +27,82 @@ type SysExtentCSum struct {
 	Sums       SumRun
 }
 
+type Optional[T any] struct {
+	OK  bool
+	Val T
+}
+
+var (
+	_ json.Marshaler   = Optional[bool]{}
+	_ json.Unmarshaler = (*Optional[bool])(nil)
+)
+
+func (o Optional[T]) MarshalJSON() ([]byte, error) {
+	if o.OK {
+		return json.Marshal(o.Val)
+	} else {
+		return []byte("null"), nil
+	}
+}
+
+func (o *Optional[T]) UnmarshalJSON(dat []byte) error {
+	if string(dat) == "null" {
+		*o = Optional[T]{}
+		return nil
+	}
+	o.OK = true
+	return json.Unmarshal(dat, &o.Val)
+}
+
+type QualifiedPhysicalAddr struct {
+	Dev  uint64
+	Addr int64
+}
+
+type Mapping struct {
+	LAddr      int64
+	PAddr      QualifiedPhysicalAddr
+	Size       int64
+	SizeLocked bool             `json:",omitempty"`
+	Flags      Optional[uint64] `json:",omitempty"`
+}
+
 func TestRoundTrip(t *testing.T) {
 	t.Parallel()
-	dents, err := os.ReadDir(filepath.Join("testdata", "roundtrip"))
-	require.NoError(t, err)
-	for _, dent := range dents {
-		filename := dent.Name()
-		if !strings.HasSuffix(filename, ".json") {
-			continue
-		}
-		t.Run(strings.TrimSuffix(filename, ".json"), func(t *testing.T) {
+
+	type testcase struct {
+		ObjPtr any
+		Cfg    lowmemjson.ReEncoderConfig
+	}
+	testcases := map[string]testcase{
+		"scandevices": {
+			ObjPtr: new(ScanDevicesResult),
+			Cfg: lowmemjson.ReEncoderConfig{
+				Indent:                "\t",
+				ForceTrailingNewlines: true,
+				CompactIfUnder:        16,
+			},
+		},
+		"mappings": {
+			ObjPtr: new([]Mapping),
+			Cfg: lowmemjson.ReEncoderConfig{
+				Indent:                "\t",
+				ForceTrailingNewlines: true,
+				CompactIfUnder:        120,
+			},
+		},
+	}
+
+	for tcName, tc := range testcases {
+		tcName := tcName
+		tc := tc
+		t.Run(tcName, func(t *testing.T) {
 			t.Parallel()
-			inBytes, err := os.ReadFile(filepath.Join("testdata", "roundtrip", filename))
+			inBytes, err := os.ReadFile(filepath.Join("testdata", "roundtrip", tcName+".json")) // #nosec G304
 			require.NoError(t, err)
-			var obj ScanDevicesResult
-			require.NoError(t, lowmemjson.NewDecoder(bytes.NewReader(inBytes)).DecodeThenEOF(&obj))
+			require.NoError(t, lowmemjson.NewDecoder(bytes.NewReader(inBytes)).DecodeThenEOF(tc.ObjPtr))
 			var outBytes bytes.Buffer
-			require.NoError(t, lowmemjson.NewEncoder(lowmemjson.NewReEncoder(&outBytes, lowmemjson.ReEncoderConfig{
-				Indent:                "\t",
-				ForceTrailingNewlines: true,
-				CompactIfUnder:        16, //nolint:gomnd // This is what looks nice.
-			})).Encode(obj))
+			require.NoError(t, lowmemjson.NewEncoder(lowmemjson.NewReEncoder(&outBytes, tc.Cfg)).Encode(tc.ObjPtr))
 			require.Equal(t, string(inBytes), outBytes.String())
 		})
 	}